There are different types of Address Books. You can create your own, be subscribed to other books, or create groups.
Groups: Are used to sort and manage your contacts for easy reference. You can create groups for such contacts as “Friends”, “Coworkers”, “Family”, etc.
Address Books: Are used to create email lists, which can be shared across the domain. Once a contact list is shared, others can subscribe and view the contents of your shared list.   
To create a new Address Book:
Select the 
Add 
 icon.   
Select Save.   
Once the address book has been saved, it will appear under the address books sub-menu. Click on the title to edit sharing and permissions.  
(Shared Address Books: Are email lists that you have created and made public. Once an address book is made public, others can subscribe and view the details of the list.)  
To share your address book, click the drop-down under "Share with all domain users" to choose from a list of options.
You can also share with specific users and assign specific permissions to each user you add separately.
This feature can be toggled on or off when editing a contact. You cannot remove a shared contact that has not been added by you.